Perkins New 1000 Series, Workshop Manual, Page: 264 / 290

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264 Workshop Manual, TPD 1350, issue 3
New 1000 Series
Fault diagnosis
The alternator is designed in such a way that a flow of
current (indicated by no light at the warning light or a
reading shown on an ammeter) shows that the
system is in correct operation. If the system is in
correct operation, no open circuit, voltage or current
output checks need to be done on the installation
unless:
! The warning light does not show when the
alternator is stationary and the switch is in the "on"
position or it shows a light when the alternator is in
operation.
! No charge current is shown on the ammeter.
! The battery is discharged.
! The battery is hotter than normal which is an
indication of loss of voltage control.
If one or more of the above symptoms occur, the
procedure indicated below should be applied.
1 Ensure that the battery is fully charged.
2 Connect a moving-coil voltmeter of good quality,
with a range of 0-50 volts, across the positive and
negative terminals of the alternator. If an ammeter is
not fitted in the electrical circuit, fit a moving-coil
ammeter of good quality, with a range of 0-100
ampere, in the wire between the alternator and the
positive terminal of the battery.
3 Turn the warning light switch to the "on" position
(main switch on instrument panel); the warning light
should be illuminated.
4 Switch on a 10-15 ampere load, for example, lights,
fans, etc.
5 Start the engine and operate it at a fast idle speed;
either the warning light should be extinguished or the
ammeter indicates a small change in the current in
relationship to the engine speed.
6 Increase the engine speed for a moment to near
maximum speed, when the charge current should be
approximately equal to the rating for the alternator, as
shown in the data and dimensions.
7 Operate the alternator at approximately half speed
(engine speed approximately 1500 rev/min) and
remove the electrical load. The voltage should go up
to 14 volts for a 12 volt system or 28 volts for a 24 volt
system and then remain constant. At the same time
the current reading should show a reduction.
Any change in the above data can indicate a fault and
the procedure that follows should be used before any
components are disconnected. This procedure is not
suitable for A127 alternators and, if a fault is found,
the alternator should be removed for test by a
specialist.
The regulator is a sealed unit and a repair is not
possible. If there is a regulator fault, the regulator
must be renewed.
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